One’s walk is based on one’s thought (v. 17). The reprobates have a reprobate mind (Rom. 1:28), and the elect have the mind of Christ I Cor. 2:16). The heart is the core of one’s thoughts, and for the reprobate their understanding is darkened, ignorant, and blind, because they are “alienated from the life of God.” (v. 18) They are “past feeling, having given themselves over to lewdness, to work all uncleaness with greediness.” (v. 19 cf. Rom. 1:24-31)
The New Geneva Study Bible drives home a valuable point on these verses in comparison to Romans 1. While the latter views reprobation from God’s side, in Ephesians Paul views it from the human side, which is similar to the Exodus referral. “In Exodus God is said to harden Pharaoh’s heart (e.g., Ex. 4:27; 7:3), but Pharaoh also hardens his own heart (Ex. 8:15, 32; 9:34).” (1867) Pharaoh was only free within the world of God’s sovereignty.